View angle adjustment mechanism in view device

ABSTRACT

This invention relates to a view angle adjustment mechanism that causes a view element tilting section holding a view element to be supported by a tilting support section via a forcible fitting-type pivot to perform view angle adjustment. A pivot is assembled by forcible fitting between a pivot convex and a pivot concave. The pivot convex includes a spherical surface. The pivot concave includes a surface formed by arranging two conical surfaces so as to face in respective directions opposite to each other along a center axis X of the pivot concave. The spherical surface of the pivot convex is inscribed in the two conical surfaces of the pivot concave.

The disclosure of Japanese Patent Application No. JP2016-071800 filed onMar. 31, 2016 including the specification, drawings, claims and abstractis incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a view angle adjustment mechanism in a viewdevice including a view element such as a mirror or a camera. In thisview angle adjustment mechanism, a view element tilting section holdinga view element is supported by a tilting support section via a forciblefitting-type pivot to perform view angle adjustment (view directionadjustment). The view angle adjustment mechanism of this inventionenables stabilization of an operating torque for view angle adjustment.

Description of the Related Art

As one kind of view devices, there is a mirror device for a vehicle. Asconventional mirror surface angle adjustment mechanisms (view angleadjustment mechanisms) that cause a mirror tilting section (view elementtilting section) to be supported by a tilting support section via aforcible fitting-type pivot to perform mirror surface angle adjustment(view angle adjustment) in a mirror device for a vehicle, there arethose described in Japanese Patent Laid-Open Nos. 2014-234112,2007-168627 and 2003-002118. The forcible fitting-type pivot in each ofthese conventional mirror surface angle adjustment mechanisms has astructure in which a convex spherical surface and a concave sphericalsurface are fitted together.

In each of the forcible fitting-type pivots described in Japanese PatentLaid-Open Nos. 2014-234112, 2007-168627 and 2003-002118, if at least oneof the convex spherical surface and the concave spherical surface ispoor in dimensional accuracy, both spherical surfaces do not abut andslide on the entire spherical surface each other, resulting in easyfluctuation in operating torque for mirror surface angle adjustment.

This invention is intended to solve the aforementioned problem in theconventional techniques and provide a view angle adjustment mechanismincluding a forcible fitting-type pivot, the view angle adjustmentmechanism enabling stabilization of an operating torque for view angleadjustment.

SUMMARY OF THE INVENTION

A view angle adjustment mechanism in a view device according to thisinvention is configured to support a view element tilting sectionholding a view element by a tilting support section via a pivot, so asto be capable to adjusting a view angle of the view element, wherein:the pivot is assembled by forcible fitting between a pivot convex and apivot concave; the pivot convex includes a spherical surface; the pivotconcave includes a surface formed by arranging two conical surfaces soas to face in respective directions opposite to each other along acenter axis of the pivot concave; and the spherical surface of the pivotconvex is inscribed in the two conical surfaces of the pivot concave.According to this invention, the spherical surface of the pivot convexis inscribed in and slides on the two conical surfaces of the pivotconcave, whereby an operating torque for view angle adjustment isstabilized.

In this invention, at least one of the pivot convex and the pivotconcave may be divided in a circumferential direction by a slit formedin an axial direction in the at least one of the pivot convex and thepivot concave. Accordingly, the slit makes elastic deformation of the atleast one of the pivot convex and the pivot concave easy, enablingprovision of forcible fitting with less backlash, whereby the operatingtorque is further stabilized.

In this invention, the slit of the pivot concave may be formed at eachof three positions equally spaced in the circumferential direction.Accordingly, the pivot concave is equally divided into three in thecircumferential direction, ensuring centering (state in which a centerposition of rotation is fixed) of the pivot compared to other numbers ofdivisions.

In this invention, a gap formed between the pivot convex and the pivotconcave at a position between two positions at which the pivot convex isinscribed in the pivot concave may form a grease reservoir. Accordingly,the gap formed between the pivot convex and the pivot concave at theposition between the two positions at which the pivot convex isinscribed in the pivot concave can effectively be used as a greasereservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view illustrating an embodiment of atilting device of a left door mirror for a vehicle, in which a mirrorsurface angle adjustment mechanism according to this invention isincorporated;

FIG. 2 is a front view illustrating an assembled state of the tiltingsupport section 12 in FIG. 1;

FIG. 3 is a right side view of the tilting support section 12 in FIG. 2;

FIG. 4 is a back view illustrating an assembled state of the tiltingdevice 10 in FIG. 1;

FIG. 5 is a diagram of a cross-section of the tilting device in FIG. 4taken along arrow A-A, the cross-section being rotated by 180 degrees,where a mirror surface angle is in a neutral position;

FIG. 6 is a diagram illustrating the cross-section in the same positionas that of FIG. 5 where the mirror surface angle is at a maximum angleposition in a left direction;

FIG. 7 is a diagram illustrating the cross-section in the same positionas that of FIG. 5, where the mirror surface angle is in a maximum angleposition in a right direction;

FIG. 8 is a cross-sectional view illustrating the tilting device in theassembled state in FIG. 4 attached to a mirror housing 82 (visor);

FIG. 9 is a front-side perspective view illustrating the mirror holder16 in FIG. 1 alone;

FIG. 10 is a back-side perspective view of the mirror holder in FIG. 9;

FIG. 11 is a front view of the mirror holder in FIG. 9;

FIG. 12 is a back view of the mirror holder in FIG. 9;

FIG. 13 is a right side view of the mirror holder in FIG. 9;

FIG. 14 is a front view of the housing front 22A in FIG. 1 alone;

FIG. 15 is a front view of worm-equipped motors and worm wheels disposedin the housing front in FIG. 14;

FIG. 16 is a perspective view of the housing rear 22B in FIG. 1 alone asviewed from the front side;

FIG. 17 is a back view of the housing rear in FIG. 16;

FIG. 18 is a cross-sectional view of the pivot convex 58 in FIG. 16 cutalong a plane extending through a center axis V of the pivot convex 58;

FIG. 19 is a cross-sectional view of the pivot concave 60 in FIG. 10 cutalong a plane extending through a center axis X of the pivot concave 60:

FIG. 20 is a diagram illustrating the pivot convex in FIG. 18 and thepivot concave in FIG. 19 forcibly fitted together, and is across-sectional view at the position that is the same as that of FIGS.18 and 19 where a mirror tilting section is in a neutral position;

FIG. 21 is a diagram of the forcible fitting part in FIG. 20 where themirror tilting section 14 is tilted in the left direction from the statein FIG. 20, and is a cross-sectional view at a position that is the sameas that of FIG. 20;

FIGS. 22 to 25 are cross-sectional views illustrating operation of anelastic piece 113, which is illustrated in, e.g., FIGS. 10 and 13, andfrom among the figures, FIG. 22 illustrates a state in which the mirrortilting section 14 is tilted to a maximum angle position in the leftdirection (state in FIG. 6);

FIG. 23 is a cross-sectional view illustrating a state in which themirror tilting section 14 is tilted slightly in the right directionsubsequent to the state in FIG. 22;

FIG. 24 is a cross-sectional view illustrating a state in which themirror tilting section 14 is further tilted in the right direction andreaches the neutral position subsequent to the state in FIG. 23 (statein FIG. 5);

FIG. 25 is a cross-sectional view illustrating a state in which themirror tilting section 14 is tilted to a maximum angle position in aright direction (state in FIG. 7) subsequent to the state in FIG. 24;

FIG. 26 is a perspective view illustrating a detailed configuration of aworm wheel 32 or 34 in FIG. 1;

FIG. 27 is a perspective view of a detailed configuration of anadjustment nut 36 or 38 in FIG. 1 as viewed from obliquely above;

FIG. 28 is a perspective view of the adjustment nut in FIG. 27 as viewedobliquely from below;

FIG. 29 is a bottom view of the adjustment nut in FIG. 27;

FIG. 30 is an enlarged cross-sectional view of an area around anadjustment nut in the state in FIG. 7 in which the mirror tiltingsection is tilted to the maximum angle position in the right direction;and

FIG. 31 is a perspective view of a modification of the pivot convex 58of the housing rear 22B in FIG. 1, instead of the structure in FIG. 16,as viewed from the front side.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of this invention will be described. FIG. 1 is an explodedperspective view of a tilting device 10 of a left-side door mirror for avehicle to which this invention is applied. This tilting device 10 has astructure based on tilting devices described in Japanese PatentLaid-Open Nos. 2014-159221 and 2014-159222 relating to patentapplications filed by the present applicant. The tilting device 10includes a tilting support section 12 and a mirror tilting section 14.The tilting support section 12 is attached to the inside of an openingof a non-illustrated mirror housing (visor). The mirror tilting section14 is formed by fitting a mirror 18 (mirror plate) into a recess 16 a ina front surface of the mirror holder 16 formed by integral molding usinga synthetic resin. The mirror tilting section 14 is joined and supportedby a front surface of the tilting support section 12 via pivots toperform mirror surface angle adjustment by means of electromotivedriving. The tilting support section 12 includes an actuator housing 22of a synthetic resin. The actuator housing 22 has a front and reartwo-split structure of a housing front 22A disposed on the front side ofa vehicle and a housing rear 22B disposed on the rear side of thevehicle. The housing front 22A and the housing rear 22B are fittedtogether and thereby integrated. The housing front 22A has a bowl-likeshape having a round front surface. In the bowl of the housing front 22Atwo male thread members 24, 26 are provided in an erected manner atrespective positions off a center of the bowl, integrally with thehousing front 22A. The male thread member 26 is disposed at a positionrotated by 90 degrees from the male thread member 24 relative to thecenter of the bowl. In respective outer circumferential surfaces of themale thread members 24, 26, respective male threads are formed over anentire length in an axial direction of the male thread members 24, 26.

In the bowl of the housing front 22A, two direct-current motors 28 (forleftward/rightward tilting) and 30 (for upward/downward tilting), andworm wheels 32, 34 (gear member), and the adjustment nuts 36, 38 (nutmembers) are received. The motors 28, 30 are received and held inrespective rectangular recesses 40, 42. The adjustment nuts 36, 38coaxially and rotatably cover respective free ends (upper ends) of themale thread members 24, 26 and are threadably connected to therespective male threads of the outer circumferential surfaces of themale thread members 24, 26. Consequently, the adjustment nuts 36, 38rise/fall (advance/withdraw) along the respective male thread members24, 26 according to directions of rotation of the adjustment nuts 36,38. In the bowl of the housing front 22A, round recesses 46, 48 areformed coaxially with the respective male thread members 24, 26. Bottomsof the worm wheels 32, 34 are rotatably received and held in therespective recesses 46, 48. Worms 50, 52 are fitted on respective rotaryshafts of the motors 28, 30. The worm wheels 32, 34 engage with therespective worms 50, 52 and are driven to rotate by the respectivemotors 28, 30. The adjustment nuts 36, 38 are coupled to the respectiveworm wheels 32, 34 so as to be unrotatable relative to the worm wheels32, 34 (rotatable integrally with the worm wheels 32, 34) and be movablein respective axial directions of the worm wheels 32, 34. Therefore,upon rotation of the motors 28, 30, the adjustment nuts 36, 38 arerotated via the worms 50, 52 and the worm wheels 32, 34. As a result,the adjustment nuts 36, 38 rise/fall (advance/withdraw) along therespective male thread members 24, 26 according to directions of therotation of the adjustment nuts 36, 38.

The housing rear 22B is put and fitted on the front surface of thehousing front 22A. Consequently, a tilting actuator 53 formed of themotors 28, 30, the worms 50, 52, the worm wheels 32, 34 and theadjustment nuts 36, 38 are received in an inner space of the actuatorhousing 22 formed of the housing front 22A and the housing rear 22B.Here, the worm wheels 32, 34 are each prevented from moving in an axialdirection by the housing rear 22B and thereby only allowed to rotatearound the axis. Also, convex spheres 36 a, 38 a at respective frontends of the adjustment nuts 36, 38 protrude outside the actuator housing22 from respective openings 54, 56 formed at respective positions off acenter position of the housing rear 22B.

The mirror tilting section 14 is tiltably held by a front surface of theactuator housing 22. In other words, a pivot convex 58 is formed at acenter of the front surface of the housing rear 22B, and a pivot concave60 (FIG. 10) is formed at a center of a back surface (rear surface) ofthe mirror holder 16. Spherical-joint coupling of the pivot convex 58and the pivot concave 60 by means of forcible fitting causes the mirrorholder 16 to be held by the housing rear 22B so as to be tiltablerightward/leftward of the vehicle and upward/downward of the vehiclerelative to the housing rear 22B. Around the pivot convex 58 in thefront surface of the housing rear 22B, four rotation-preventingprotrusions 62 are provided in a protruding manner at respectiveequally-spaced positions (positions equally spaced by 90 degrees) in acircumferential direction of the pivot convex 58. Around the pivotconcave 60 of the mirror holder 16, four rotation-preventing holes 64are provided so as to open at respective equally-spaced positions in acircumferential direction of the pivot concave 60 (positions equallyspaced by 90 degrees), corresponding to the rotation-preventingprotrusions 62, With the pivot convex 58 and the pivot concave 60forcibly fitted together, the respective rotation-preventing protrusions62 are movably inserted into the respective rotation-preventing holes 64in a depth direction of the rotation-preventing holes 64. Consequently,the mirror tilting section 14 tilts in such a manner that the mirrortilting section 14 is prevented from rotating relative to the tiltingsupport section 12. In the back surface of the mirror holder 16, concavespheres 66, 68 (FIG. 10) are formed at respective positions at which theconcave spheres 66, 68 face the respective convex spheres 36 a, 38 a atthe front ends of the adjustment nuts 36, 38. The convex spheres 36 a,38 a are fitted in and thereby coupled to the concave spheres 66, 68,respectively, as spherical joints. As a result, an angle in a horizontaldirection of the mirror surface is adjusted according to a position towhich the adjustment nut 36 has risen/fallen relative to the male threadmember 24. Also, an angle in a vertical direction of the mirror surfaceis adjusted according to a position to which the adjustment nut 38 hasrisen/fallen relative to the male thread member 26.

The tilting device 10 in FIG. 1 is assembled, for example, as follows.With respect to the tilting support section 12, the motors 28, 30 fittedwith the worms 50, 52 are received in the respective recesses 40, 42 ofthe housing front 22A of the tilting support section 12. The adjustmentnuts 36, 38 are screwed onto the respective male thread members 24, 26.The worm wheels 32, 34 are coaxially inserted outside of the adjustmentnuts 36, 38, and the lower parts of the worm wheels 32, 34 are rotatablyheld in the respective recesses 46, 48. At this time, the worm wheels32, 34 engage with the respective worms 50, 52. The housing rear 22B isput on the housing front 22A, and the housing front 22A and the housingrear 22B are tentatively coupled. This tentative coupling is performedby detachably engaging two claws 70 formed in a protruding manner at acenter on the back side of the housing rear 22B with a claw engagementportion 72 formed at a center of the housing front 22A in FIG. 5.Consequently, the tilting support section 12 is assembled as in FIG. 2(state as viewed from the front) and FIG. 3 (state as viewed from theright side). The engagement of the two claws 70 with the claw engagementportion 72 can be viewed through a hole 58 a provided at a center of thepivot convex 58 in FIG. 2. Also, the engagement can be viewed in arecess 73 formed at a center of the housing front 22A in FIG. 4.

Meanwhile, with respect to the mirror tilting section 14, the mirror 18is fitted and set in the recess 16 a in the front surface of the mirrorholder 16 in FIG. 1. Consequently, the mirror tilting section 14 isassembled. In general, a butyl rubber double-sided tape is attached tobetween opposed surfaces of the mirror 18 and the mirror holder 16 tosuppress chatter vibration of the mirror surface. However, in thisembodiment, a chatter vibration suppression effect is provided by alater-described outer pivot 90, and thus, no butyl rubber double-sidedtape is used, reducing the number of components.

After the tilting support section 12 and the mirror tilting section 14being assembled, respectively, as described above, grease is charged inthe pivot concave 60. Also, grease is charged into an entirecircumference of a gap 104 (see FIG. 10) between an outer-pivot convexsurface-forming annular wall 100 and an outer auxiliary annular wall102, which will be described later. Next, the tilting support section 12and the mirror tilting section 14 are positioned in a surface directionand a rotation direction and joined. The positioning in the surfacedirection is performed by aligning respective center positions of thetilting support section 12 and the mirror tilting section 14 (that is, atip of the pivot convex 58 is brought into abutment with an entrance ofthe pivot concave 60 (FIG. 10)). The positioning in the rotationdirection is performed by alignment between a position in the rotationdirection of an alignment mark 74 formed in an outer circumferentialsurface of the housing front 22A and a position in the rotationdirection of an alignment mark 76 formed in the back surface of themirror holder 16 in FIG. 4. As a result of the positioning, the pivotconvex 58 and the pivot concave 60 face each other, the fourrotation-preventing protrusions 62 face the four rotation-preventingholes 64, respectively, and the convex spheres 36 a, 38 a of theadjustment nuts 36, 38 and the concave spheres 66, 68 of the mirrorholder 16 face each other, respectively. In this state, the tiltingsupport section 12 and the mirror tilting section 14 are stronglymanually pressed against each other in the respective directions inwhich the tilting support section 12 and the mirror tilting section 14face each other. Consequently, the pivot convex 58 and the pivot concave60 are forcibly fitted together. Also, the convex spheres 36 a, 38 a ofthe adjustment nuts 36, 38 are forcibly fitted in the concave spheres66, 68 of the mirror holder 16, respectively. Also, the fourrotation-preventing protrusions 62 are inserted into the fourrotation-preventing holes 64, respectively. Consequently, the tiltingsupport section 12 and the mirror tilting section 14 are joined to eachother without screw fastening. Consequently, the tilting device 10 isassembled in the state in FIGS. 4 and 5 (diagrams of the cross-sectionalong arrow A-A in FIG. 4, the cross-section being rotated by 180degrees).

The tilting device 10 assembled as described above will be describedwith reference to FIG. 5. An inner pivot 88 and an outer pivot 90, whichare concentric to each other and have different diameters, are formedbetween the tilting support section 12 and the mirror tilting section14. The inner pivot 88 is formed by the pivot convex 58 and the pivotconcave 60 being forcibly fitted together. The outer pivot 90 isassembled by the forcible fitting in the inner pivot 88. The outer pivot90 has a structure in which an outer-pivot convex surface 92 formed atthe mirror holder 16 and an outer-pivot concave surface 94 formed at thehousing front 22A of the tilting support section 12 are slidably fittedtogether. Each of the outer-pivot convex surface 92 and the outer-pivotconcave surface 94 is a spherical surface. Each of pivot centers O ofthe inner pivot 88 and the outer pivot 90 is located in a centerposition of the sphere of the pivot convex 58. The convex sphere 36 a ofthe adjustment nut 36 is fitted in the rightward/leftward-tiltingconcave sphere 66, whereby the concave sphere 66 and the convex sphere36 a are coupled as a spherical joint. Although not illustrated in FIG.5, likewise, the convex sphere 38 a of the adjustment nut 38 is fittedin the upward/downward-tilting concave sphere 68 (FIG. 10), whereby theconcave sphere 68 and the convex sphere 38 a are coupled as a sphericaljoint.

FIG. 5 illustrates a state in which a mirror surface angle is in aneutral position. The neutral state refers to a state in which a tangentplane of the mirror 18 at a position at which a center axis V of thepivot convex 58 intersects with the mirror 18 is perpendicular to thecenter axis V. Upon the rightward/leftward-tilting motor 28 (FIG. 1)being driven to rotate the worm 50 (FIG. 1) from this state, the wormwheel 32, which forms a worm gear jointly with the worm 50, rotates. Theworm wheel 32 is held between the housing front 22A and the housing rear22B and thus is prevented from moving axially. Upon rotation of the wormwheel 32, the adjustment nut 36 rises/falls the male thread member 24while the adjustment nut 36 rotates following the rotation.Consequently, the mirror tilting section 14 is tilted with the pivotcenter O as a center, whereby mirror surface angle adjustment in thehorizontal direction is performed. FIG. 6 illustrates a state in whichthe mirror tilting section 14 is tilted to a maximum angle position in aleft direction. Also, FIG. 7 illustrates a state in which the mirrortilting section 14 is tilted to a maximum angle position in a rightdirection. Mirror surface angle adjustment in the vertical direction isperformed likewise. In other words, with reference to FIG. 1, upon theupward/downward-tilting motor 30 being driven to rotate the worm 52, theworm wheel 34, which forms a worm gear jointly with the worm 52,rotates. As with the worm wheel 32, the worm wheel 34 is prevented frommoving axially. Upon rotation of the worm wheel 34, the adjustment nut38 rises/falls the male thread member 24 while the adjustment nut 38rotates following the rotation. Consequently, the mirror tilting section14 is tilted with the pivot center O as a center, whereby mirror surfaceangle adjustment in the vertical direction is performed.

Attachment of the assembled tilting device 10 to a mirror housing(visor) is performed, for example, as follows. As illustrated in FIG. 8,the tilting device 10 is positioned at a predetermined attachmentposition inside an opening of a mirror housing 82. A support 84(reinforcement resin component) is brought into abutment with a backsurface of the mirror housing 82, and four screws 86 are firmly screwedinto respective screw holes 22Ba of the housing rear 22B throughrespective series of screw through-holes 84 a, 82 a, 22Aa of the support84, the mirror housing 82 and the housing front 22A. Positions of thefour screw through-holes 22Aa of the housing front 22A are indicated inFIG. 4. Also, positions of the screw holes 22Ba of the four housing rear22B are indicated in FIG. 2. Consequently, the housing front 22A and thehousing rear 22B are fully fastened to each other, and the tiltingdevice 10 is attached and fixed to the mirror housing 82. After theattachment, a non-illustrated housing cover (in the case of twopiece-type mirror housing) is fitted on the back surface of the mirrorhousing 82, whereby heads of the screws 86 are hidden from the outside.

Here, a detailed configuration of the mirror holder 16 will bedescribed. FIGS. 9 to 13 illustrate the mirror holder 16 alone. FIG. 9is a perspective view of the front side (side on which the mirror 18 isfitted), FIG. 10 is a perspective view of the back side, FIG. 11 is afront view, FIG. 12 is a back view, and FIG. 13 is a right side view.The mirror holder 16 is formed as an integrally-molded product of asynthetic resin such as polypropylene (PP). In the front surface (FIG.9) of the mirror holder 16, the recess 16 a that allows the mirror 18 tobe fitted therein is formed. Upon the mirror 18 being fitted in therecess 16 a, an entire circumference of an outer circumferential edge ofthe mirror 18 is locked by a fold rim 16 b of a circumferential edge ofthe recess 16 a, and pressing protrusions 95 a, 95 b formed inrespective areas of an outer circumference of the front surface of themirror holder 16 press and abuts on a back surface of the mirror 18.Consequently, the mirror 18 is stably held in the mirror holder 16. Eachof the pressing protrusions 95 a is a protrusion provided directly atthe front surface of the mirror holder 16 in a protruding manner. Also,each of the pressing protrusions 95 b is a protrusion formed on anelastic piece 16 c formed in a cantilever-supported manner by cutting asurface of the mirror holder 16. At the center of the back surface (FIG.10) of the mirror holder 16, a pivot concave annular wall 96 forming thepivot concave 60 of the inner pivot 88 is formed in a protruding manner.Three slits 98 are formed at respective positions equally spaced(equally spaced by 120 degrees) in a circumferential direction of thepivot concave annular wall 96, whereby the pivot concave annular wall 96are divided in three in the circumferential direction. The slits 98 makeelastic deformation of the pivot concave annular wall 96 easy.Therefore, in the state where the pivot convex 58 forcibly fitted in thepivot concave 60, the pivot convex 58 can be held in the pivot concave60 with less backlash. In addition, the number of divisions is three,ensuring centering of the pivot. In the forcibly fitted state, the pivotconcave annular wall 96 catches (grabs) the pivot convex 58 by means ofan elastic force thereof, providing a predetermined pressing force tothe pivot convex 58. Also, since the pivot concave annular wall 96easily elastically deforms, the support of the mirror tilting section 14by the outer pivot 90 is uniformized in a circumferential direction ofthe outer pivot 90. In other words, if the support of the mirror tiltingsection 14 by the outer pivot 90 is biased in the circumferentialdirection of the outer pivot 90, a pressing force generated by the biasacts on the pivot concave annular wall 96, which causes elasticdeformation of the pivot concave annular wall 96. As a result, the biasis corrected, and the support of the mirror tilting section 14 by theouter pivot 90 is uniformized in the circumferential direction of theouter pivot 90, providing a chatter vibration suppression effect. Thefour rotation-preventing holes 64 are formed just on the outercircumferential side of the pivot concave annular wall 96. At the backsurface of the mirror holder 16, the outer-pivot convex surface-formingannular wall 100 forming the outer pivot 90 is formed continuouslyaround an entire circumference of 360 degrees in a protruding manner onthe outer circumferential side of the pivot concave annular wall 96.Furthermore, the outer auxiliary annular wall 102 is formed continuouslyaround an entire circumference of 360 degrees in a protruding manner onthe outer circumferential side of the outer-pivot convex surface-formingannular wall 100. The pivot concave annular wall 96, the outer-pivotconvex surface-forming annular wall 100 and the outer auxiliary annularwall 102 are disposed concentrically to one another. A gap 104 is formedcontinuously around an entire circumference of 360 degrees between theouter-pivot convex surface-forming annular wall 100 and the outerauxiliary annular wall 102. An outer-pivot concave surface-formingannular wall 123 (FIG. 1) of the housing front 22A is received in thegap 104 in such a manner that the outer-pivot concave surface-formingannular wall 123 can move into/out from the gap 104 according to tiltingof the mirror tilting section 14, and thus, the outer-pivot concavesurface-forming annular wall 123 moves (swings) in the gap 104. In anarea, between the pivot concave annular wall 96 and the outer-pivotconvex surface-forming annular wall 100, of the back surface of themirror holder 16, the concave spheres 66, 68 that allow the convexspheres 36 a, 38 a of the adjustment nuts 36, 38 to be forcibly fittedtherein are disposed. For the forcible fitting, a slit is formed at eachof three positions in a circumferential direction of each of the concavespheres 66, 68. As clearly indicated in FIG. 6 for example, a generalplate thickness t1 (for example, 3 mm) of the area, between the pivotconcave annular wall 96 and the outer-pivot convex surface-formingannular wall 100, of the plate of the mirror holder 16 is set to belarger than a general plate thickness t2 (for example, 2 mm) of an areaon the outer circumferential side of the outer-pivot convexsurface-forming annular wall 100. Consequently, a stiffness of an areaof the mirror holder 16, the area being coupled to the tilting supportsection 12, is enhanced, enabling provision of a mirror surfacevibration suppression effect. Also, a stiffness of the area on the outercircumferential side of the mirror holder 16 is decreased, enabling themirror 18 to be easily fitted into the mirror holder 16.

In FIG. 10, the outer-pivot convex surface-forming annular wall 100includes an annular wall body 100 a forming the outer-pivot convexsurface 92, and an inner auxiliary annular wall 100 b disposed on theinner circumferential side of the annular wall body 100 a. A top of theannular wall body 100 a and a top of the inner auxiliary annular wall100 b are coupled in an entire circumference of 360 degrees. As viewedfrom the front side (FIG. 9) of the mirror holder 16, the annular wallbody 100 a and the inner auxiliary annular wall 100 b are disposedconcentrically to each other across a space 111 (opening) having apredetermined width in a radial direction around the entirecircumference of 360 degrees. In this way, the outer-pivot convexsurface-forming annular wall 100 has a dual structure formed of theannular wall body 100 a and the inner auxiliary annular wall 100 b.Consequently, a stiffness of the outer-pivot convex surface-formingannular wall 100 is enhanced.

As illustrated in, e.g., FIGS. 10 and 12, in the annular wall body 100a, five elastic pieces 113 are formed at respective equally-spacedpositions (positions equally spaced by 72 degrees) in thecircumferential direction of the spaced annular wall body 100 a. Eachelastic piece 113 is formed by cutting the annular wall body 100 a, andis supported in a cantilevered manner on the annular wall body 100 a. Aprotrusion 113 a is formed at a center of an outward-directed surface ofeach elastic piece 113. A top of the protrusion 113 a of each elasticpiece 113 slidably and elastically abuts on the outer-pivot concavesurface 94 (e.g., FIGS. 1 and 5) formed at the tilting support section12. Consequently, the mirror tilting section 14 is not only supported bythe tilting support section 12 via the inner pivot 88 but also iselastically supported by the tilting support section 12 via the outerpivot 90, enabling suppression of mirror surface vibration caused by,e.g., a wind generated by movement of the vehicle or vibration of thevehicle. At this time, the elastic pieces 113 abut on the outer-pivotconcave surface 94 by means of point contact via the protrusions 113 a,enabling reduction in slide resistance between the elastic pieces 113and the outer-pivot concave surface 94 and in addition, enabling makingthe slide resistance constant by absorption of piece-to-piece variations(molding errors). Also, since the five elastic pieces 113 are disposedat the respective equally-spaced positions (positions equally-spaced by72 degrees) in the circumferential direction of the outer-pivot convexsurface-forming annular wall 100, even if a support failure occurs inone of the elastic pieces 113, the mirror tilting section 14 can besupported on a half or more of the outer-pivot concave surface 94 viathe remaining four elastic pieces 113. Therefore, an extreme decrease inperformance of the support of the mirror tilting section 14 by the outerpivot 90 is prevented. Here, as a result of the elastic pieces 113 beingformed by cutting the annular wall body 100 a, the annular wall body 100a includes holes. However, since the inner auxiliary annular wall 100 bwith no holes is disposed on the inner circumferential side of theannular wall body 100 a, which suppresses entry of, e.g., foreignsubstances and/or water into space on the inner circumferential siderelative to the outer pivot 90.

As illustrated in FIG. 9, in the space 111, between the annular wallbody 100 a and the inner auxiliary annular wall 100 b, of theouter-pivot convex surface-forming annular wall 100, a plurality of ribs115 joining the annular wall body 100 a and the inner auxiliary annularwall 100 b are disposed at appropriate intervals. The stiffness of theouter-pivot convex surface-forming annular wall 100 is further enhancedby the ribs 115. In particular, the ribs 115 are disposed at respectivepositions on the right and left sides (in the circumferential direction)of the respective elastic pieces 113 in the annular wall body 100 a, thepositions being close to the respective elastic pieces 113, and thus,decrease in stiffness of the annular wall body 100 a resulting from theelastic pieces 113 being formed by cutting the annular wall body 100 acan be compensated for by the ribs 115.

Next, a detailed configuration of the housing front 22A will bedescribed. FIG. 14 is a front view of the housing front 22A alone. Thehousing front 22A is an integrally-molded product of a synthetic resinsuch as ABS resin and is formed in a bowl-like shape as mentioned above.The housing front 22A includes a flat portion 121 on the innercircumferential side and a curved outer-pivot concave surface-formingannular wall 123 on the outer circumferential side, which are separatedfrom each other in a radial direction with a predetermined radialposition 119 as a boundary. In the flat portion 121, as described above,e.g., the rectangular recesses 40, 42 that receive and hold the motors28, 30, the round recesses 46, 48 that rotatably receive and hold thelower parts of the worm wheels 32, 34, the four screw through-holes 22Aaand the claw engagement portion 72 are formed. The two claws 70 (e.g.,FIGS. 2, 4, 5 and 17) of the housing rear 22B engage with the clawengagement portion 72. The engagement causes the housing front 22A andthe housing rear 22B to be tentatively coupled. The two claws 70, 70 ofthe housing rear 22B enter holes 71, 71 on the opposite, right and left,sides of the claw engagement portion 72 and detachably engage withright/left parts of the claw engagement portion 72, respectively. Aninner circumferential surface of the outer-pivot concave surface-formingannular wall 123 is a spherical surface, and the inner circumferentialsurface forms the outer-pivot concave surface 94. At a position partwayin a radial direction of the outer-pivot concave surface 94, acircumferentially-extending groove 117 is formed. This groove 117 formsa grease reservoir of the outer pivot 90. The grease reservoir 117discontinues at five circumferentially equally-spaced parts 117 a(equally spaced by 72 degrees). These ungrooved parts 117 a are partsthat allow the protrusions 113 a of the respective elastic pieces 113(e.g., FIGS. 10 and 3) to slide thereon. In order not to hinder thesliding, the groove 117 is eliminated in the ungrooved parts 117 a. FIG.15 illustrates a state in which the motors 28, 30 are received and heldin the recesses 40, 42 and the worm wheels 32, 34 are received in therecesses 46, 48. The worms 50, 52 fitted on the rotary shafts of themotors 28, 30 engage with the worm wheels 32, 34, respectively.

Next, a detailed configuration of the housing rear 22B will bedescribed. FIG. 16 is a perspective view of the housing rear 22B aloneas viewed from the front side, and FIG. 17 is a back view of the housingrear 22B. As with the housing front 22A, the housing rear 22B is formedas an integrally-molded product of a synthetic resin such as ABS resin.In FIG. 16, the pivot convex 58 is formed in a protruding manner at thecenter of the front surface of the housing rear 22B. Four grooves 125extending in a direction of the center axis V of the pivot convex 58 areformed at respective positions equally-spaced in the circumferentialdirection (positions equally-spaced by 90 degrees) in an outercircumferential surface of the pivot convex 58. The fourrotation-preventing protrusions 62 are formed in a protruding manner atthe respective positions surrounding the pivot convex 58 in the frontsurface of the housing rear 22B. Furthermore, in the housing rear 22B,e.g., the openings 54, 56 and the screw holes 22Ba are formed. Theadjustment nuts 36, 38 move into/out from the respective openings 54,56. The four screws 86 (FIG. 8) are screwed into the respective screwholes 22Ba. The four screws 86 fasten the housing front 22A and thehousing rear 22B to each other and attach and fix the tilting device 10to the mirror housing 82. In FIG. 17, the aforementioned two claws 70are provided in a protruding manner at the center of the back surface ofthe housing rear 22B. Four bosses 127 are provided in a protrudingmanner at an outer circumference of the back surface of the housing rear22B. In these bosses 127, the aforementioned screw holes 22Ba areprovided along respective center axes thereof. Upon the housing rear 22Bbeing put on the housing front 22A and then being depressed, the twoclaws 70 engage with the claw engagement portion 72 (e.g., FIGS. 2, 4, 5and 14) of the housing front 22A. Consequently, the housing front 22Aand the housing rear 22B are fitted together and tentatively coupled toeach other. Consequently, the tilting actuator 53 (FIG. 1) disposed onthe flat portion 121 (FIG. 15) of the housing front 22A is received inthe inner space of the actuator housing 22 formed of the housing front22A and the housing rear 22B. At this time, only the convex spheres 36a, 38 a of the adjustment nuts 36, 38 protrude from the respectiveopenings 54, 56 of the housing rear 22B. Also, the four screwthrough-holes 22Aa of the housing front 22A and the four screw holes22Ba of the housing rear 22B communicate with each other, respectively.

Surface shapes of the pivot convex 58 and the pivot concave 60 of theinner pivot 88 will be described. FIG. 18 illustrates a convex surfaceshape of the pivot convex 58. Alternate long and short dash line Vindicates the center axis of the pivot convex 58. An upper area 129 aand a lower area 129 c of the outer circumferential surface (convexsurface 129) of the pivot convex 58 are formed of respective sphericalsurfaces having a same radius with the pivot center O as a center. Anintermediate area 129 b of the outer circumferential surface (convexsurface 129) of the pivot convex 58 between the upper area 129 a and thelower area 129 c is formed of a cylindrical surface with a center axis Xas a center axis. FIG. 19 illustrates a concave surface shape of thepivot concave 60 (shape when the pivot convex 58 is fitted in the pivotconcave 60). Alternate long and short dash line X indicates a centeraxis of the pivot concave 60. An upper area 131 a of an innercircumferential surface (concave surface 131) of the pivot concave 60 isformed of a conical surface of a partial area along the center axis X ofa cone having an apex on the upper side. Also, a lower area 131 c of theinner circumferential surface (concave surface 131) of the pivot concave60 is formed of a conical surface of a partial area along the centeraxis X of a cone having an apex on the lower side. An apex angle of thecone in the upper area 131 a and an apex angle of the cone in the lowerarea 131 c are equal to each other. Cone axes of the conical surfaces ofthe upper area 131 a and the lower area 131 c coincide to the centeraxis X. A length of the lower area 131 c in a direction along the centeraxis X is shorter than a length of the upper area 131 a in the samedirection. The intermediate area 131 b of the inner circumferentialsurface (concave surface 131) of the pivot concave 60 between the upperarea 131 a and the lower area 131 c is formed of a cylindrical surfacewith the center axis X as a center axis. Respective boundary parts amongthe upper area 131 a, the intermediate area 131 b and the lower area 131c are connected by smooth curves. The apex angles of the cone in theupper area 131 a and the lower area 131 c are set so as to satisfy thefollowing conditions. In other words, line L1 connecting the upper area131 a and the pivot center O is perpendicular to a surface of the upperarea 131 a at a partway position P1 in the axis X direction in the upperarea 131 a. Also, line L2 connecting the lower area 131 c and the pivotcenter O is perpendicular to a surface of the lower area 131 c at apartway position P2 in the axis X direction in the lower area 131 c. Forexample, as illustrated in FIG. 19 each of a first conical surface areaand a second conical surface area of the concave surface 121 may have atrapezoidal shape 131T1, 131T2 with respect to a side view that isorthogonal to a cross-sectional plane taken across the center axis ofthe pivot concave.

FIG. 20 illustrates a state in which the pivot convex 58 and the pivotconcave 60 of the inner pivot 88 are forcibly fitted together. Themirror tilting section 14 is in the neutral position as indicated inFIG. 5. In this case, the respective spherical surfaces of the upperarea 129 a and the lower area 129 c of the pivot convex 58 are inscribedin (internally contact with) the respective conical surfaces of theupper area 131 a and the lower area 131 c of the pivot concave 60. Inother words, the convex surface 129 of the pivot convex 58 is inabutment with the concave surface 131 of the pivot concave 60 only viarespective entire circumferences of circumferential positions C1, C2 atthe positions P1, P2. FIG. 21 illustrates a state when the mirrortilting section 14 is tilted leftward from the state in FIG. 20. In thiscase, also, the convex surface 129 of the pivot convex 58 is in abutmentwith the concave surface 131 of the pivot concave 60 only via respectiveentire circumferences of the circumferential positions C1, C2 at thepositions P1, P2. In other words, upon the mirror tilting section 14being tilted, for the abutment positions in the convex surface 129 andthe concave surface 131, only the abutment positions in the convexsurface 129 move while the abutment positions in the concave surface 131do not move and remain at the circumferential positions C1, C2.Therefore, compared to the case where the convex surface 129 of thepivot convex 58 and the concave surface 131 of the pivot concave 60 areboth spherical surfaces and the entire spherical surfaces abut and slideon each other, it is less likely to be affected by surface accuracy andan operating torque for mirror surface angle adjustment is stabilized. Astable operating torque can be obtained even if an atmospheretemperature changes. Also, between the circumferential positions C1, C2at which the convex surface 129 and the concave surface 131 are inabutment with each other, a gap 133 is formed continuously around anentire circumference between the convex surface 129 and the concavesurface 131. Grease is charged in the gap 133 and the gap 133 thus formsa grease reservoir. The grease in the grease reservoir 133 facilitatessmooth sliding of the convex surface 129 and the concave surface 131,enabling mirror surface angle adjustment to be made with a more stableoperating torque.

Next, operation of the elastic pieces 113 formed at the outer-pivotconvex surface 92 of the outer pivot 90 will be described. FIGS. 22 to25 illustrate operation of an elastic piece 113 when the mirror tiltingsection 14 is tilted to a maximum angle position in the right directionin FIG. 7 from a state in which the mirror tilting section 14 is tiltedto a maximum angle position in the left direction in FIG. 6 through theneutral position in FIG. 5, sequentially. FIGS. 22 to 25 illustrate avertical cross-section of the outer pivot 90 at a right end position,taken along a position corresponding to a plane extending through bothcenter axes V, X of the pivot convex 58 and the pivot concave 60 and theprotrusions 113 a of the elastic pieces 113. First, FIG. 22 illustratesa state in which the mirror tilting section 14 is tilted to the maximumangle position in the left direction. At this time, at the right endposition of the outer pivot 90, an end of the outer-pivot convex surface92 and an end of the outer-pivot concave surface 94 slightly overlapeach other, and no large gap is generated between the outer-pivot convexsurface 92 and the outer-pivot concave surface 94. Also, the elasticpiece 113 at this position is released from abutment with theouter-pivot concave surface 94. Upon the mirror tilting section 14 beingtilted in the right direction from this state, an inclined surface 123 aof an upper end of the outer-pivot concave surface-forming annular wall123 of the housing front 22A and an inclined surface 113 b of a lowerend of the protrusion 113 a of the elastic piece 113 are brought intoabutment with each other at the position indicated in FIG. 23.Consequently, the inclined surfaces 123 a, 113 b slide on each otheragainst an elastic force of the elastic piece 113, and the elastic piece113 withdraws inward, and lastly, the elastic piece 113 enters the innercircumferential side of the outer-pivot concave surface-forming annularwall 123. Upon the elastic piece 113 entering the inner circumferentialside of the outer-pivot concave surface-forming annular wall 123, anapex of the protrusion 113 a is brought into abutment with theouter-pivot concave surface 94 and slides on the outer-pivot concavesurface 94. FIG. 24 illustrates a state in which the mirror tiltingsection 14 reaches the neutral position in FIG. 5. The apex of theprotrusion 113 a is in contact with the outer-pivot concave surface 94by an elastic force of the elastic piece 113 (pressing force of theelastic abutment). Also, an upper portion of the outer-pivot concavesurface-forming annular wall 123 of the housing front 22A enters the gap104 between the outer-pivot convex surface-forming annular wall 100 andthe outer auxiliary annular wall 102. Upon the mirror tilting section 14being further tilted in the right direction from this state, asillustrated in FIG. 25, the upper end of the outer-pivot concavesurface-forming annular wall 123 bumps against a far end surface 104 aat a deepest part of the inside of the gap 104, whereby the tilting ofthe mirror tilting section 14 is stopped. At this time, the mirrortilting section 14 is at the maximum angle position in the rightdirection. In this case, also, the state in which the apex of theprotrusion 113 a is in contact with the outer-pivot concave surface 94by the pressing force of the elastic abutment of the elastic piece 113is maintained.

In this embodiment, the mirror tilting section 14 is designed so as tobe capable of tilting at a maximum angle of ±13.5 to 14 degrees inrespective directions relative to the neutral position in FIG. 5. If theangle of the tilting of the mirror tilting section 14 is increased, asin FIG. 22, some of the elastic pieces 113 are released from abutmentwith the outer-pivot concave surface 94 and support via such elasticpieces 113 become ineffective. However, even in such case, at leastthree remaining elastic pieces 113 abut on the outer-pivot concavesurface 94 and can cause the outer-pivot convex surface 92 to besupported by the outer-pivot concave surface 94. In addition, in anactual use in which the present door mirror is installed in a vehicle,most of users use the door mirror at an angle of around ±5 degreesrelative to the neutral position. In this case, all of the five elasticpieces 113 abut on the outer-pivot concave surface 94, whereby theouter-pivot convex surface 92 is supported by the outer-pivot concavesurface 94 around the entire circumference.

The inner pivot 88 is assembled by forcibly fitting the pivot convex 58and the pivot concave annular wall 96 circumferentially divided intothree by the slits 98, without screw fastening. Therefore, the mirrortilting section 14 has room for slightly moving in the surface directionor the axial direction relative to the tilting support section 12 bymeans of elastic deformation of the pivot concave annular wall 96. Thus,the support of the mirror tilting section 14 by the outer pivot 90 isuniformized in the circumferential direction of the outer pivot 90,providing a favorable chatter vibration suppression effect via the outerpivot 90. Also, the outer-pivot concave surface-forming annular wall 123of the housing front 22A is inserted into the gap 104 between theouter-pivot convex surface-forming annular wall 100 and the outerauxiliary annular wall 102, and thus, entry of, e.g., foreign substancesand/or water into the space inside the outer pivot 90 is suppressed.Also, grease is charged and held in the gap 104, enhancing the effect ofsuppressing entry of, e.g., foreign substances and/or water into thespace inside the outer pivot 90. In this case, the outer circumferentialsurface of the outer-pivot convex surface-forming annular wall 100, towhich the grease adheres, is covered by the outer auxiliary annular wall102, and thus, at the time of assembling the tilting support section 12and the mirror tilting section 14, the grease adhering to the outercircumferential surface of the outer-pivot convex surface-formingannular wall 100 can be prevented from adhering to the hands of aworker.

Next, detailed configurations of the worm wheels 32, 34 and theadjustment nuts 36, 38 will be described. FIG. 26 illustrates a wormwheel 32 or 34. The worm wheel 32 or 34 is formed as anintegrally-molded product of a synthetic resin. A gear (helical gear)135 to be engaged with a worm 50 or 52 (FIG. 1) is formed at an outercircumferential surface of the lower part of the worm wheel 32 or 34. Aninner circumferential-side part of the worm wheel 32 or 34 is extendedupward and forms an extension 137. In the inner circumferential-sidepart of the worm wheel 32 or 34, axially-extending grooves 139 areformed at four positions equally spaced in a circumferential direction(positions equally spaced by 90 degrees). The grooves 139 each form acutout in the extension 137. The grooves or cutouts 139 are formedcontinuously from a lower end to an upper end of the worm wheel 32 or34.

FIGS. 27 to 29 illustrate an enlargement of an adjustment nut 36 or 38.The adjustment nut 36 or 38 is formed of an integrally-molded product ofa synthetic resin such as polyacetal (POM). At a front end of theadjustment nut 36 or 38, the convex sphere 36 a or 38 a to be coupled toa concave sphere 66 or 68 (FIG. 10) of the mirror holder 16 as aspherical joint is formed. A cylindrical barrel 140 is connected to abottom of the convex sphere 36 a or 38 a. Five legs 143 are connected toa bottom of the barrel 140. The adjustment nut 36 or 38 has suchstructure as above. Inside the adjustment nut 36 or 38, a void 141 thatallows the male thread member 24 or 26 to be withdrawably insertedthereto is formed. The void 141 opens at a rear end of the adjustmentnut 36 or 38. Five legs 143 are disposed at equal intervals (equallyspaced by 72 degrees) in a circumferential direction of the adjustmentnut 36 or 38. On the inner circumferential surface side of each leg 143,a claw 145 to be threadably connected to a male thread of a male threadmember 24 or 26 is formed. At positions in a lower portion of an outercircumferential surface of the barrel 140, immediately above the legs143, four protrusions 147 are formed so as to protrude outward. The fourprotrusions 147 are disposed at equal intervals (equally spaced by 90degrees) in the circumferential direction of the adjustment nut 36 or38. A length of the protrusions 147 in an axial direction of theadjustment nut 36 or 38 is longer than a length of the protrusions 147in the circumferential direction of the adjustment nut 36 or 38. Inother words, the protrusions 147 are flat in the circumferentialdirection of the adjustment nut 36 or 38 and elongated in the axialdirection of the adjustment nut 36 or 38.

In the tilting support section 12, the claws 145 of the adjustment nut36 or 38 are threadably connected to the male thread member 24 or 26 ofthe housing front 22A. The adjustment nut 36 or 38 is received in thespace on the inner circumferential side of the worm wheel 32 or 34. Thelower part of the worm wheel 32 or 34 is rotatably received and held inthe recess 40 or 42 of the housing front 22A. The four protrusions 147of the adjustment nut 36 or 38 are received in the four grooves orcutouts 139 of the worm wheel 32 or 34 so as to be movable along thegrooves or cutouts 139. Consequently, upon the worm wheel 32 or 34 beingrotated by motor driving, the adjustment nut 36 or 38 rotates togetherwith the worm wheel 32 or 34 via the engagement between the grooves orcutouts 139 and the protrusion 147. At this time, the claws 145 arethreadably connected to the male thread member 24 or 26 of theadjustment nut 36 or 38, and thus, the adjustment nut 36 or 38rises/falls along the male thread member 24 or 26. At this time, theprotrusions 147 move along the respective grooves or cutouts 139.

FIG. 30 illustrates an adjustment nut 36 in a state in which the mirrortilting section 14 is tilted to the maximum angle position in the rightdirection (state in FIG. 7). An inner diameter of the opening 54 of thehousing rear 22B from which the adjustment nut 36 protrudes is slightlylarger than an outer diameter of a barrel 140 of the adjustment nut 36and is smaller than an outer circumferential diameter of the protrusions147. A structure part 149 at a circumferential edge of the opening 54 ofthe housing rear 22B forms a protrusion abutment portion on which theprotrusions 147 abut. In a state in which the mirror tilting section 14is tilted to the maximum angle position in the right direction, asillustrated in FIG. 7 or 25, the upper end of the outer-pivot concavesurface-forming annular wall 123 of the housing front 22A bumps againstthe far end surface 104 a at the deepest part of the inside of the gap104 between the outer-pivot convex surface-forming annular wall 100 andthe outer auxiliary annular wall 102, whereby the tilting of the mirrortilting section 14 is stopped. In this case, in FIG. 30, the protrusions147 of the adjustment nut 36 reach tops of the respective grooves orcutouts 139 of the worm wheel 32, but do not abut on the protrusionabutment portion 149. In other words, there is a small clearance gbetween the protrusions 147 and the protrusion abutment portion 149.When replacing the mirror tilting section 14 due to, e.g., breakage ofthe mirror 18, a finger or fingers are inserted under a left end of themirror tilting section 14 in FIG. 7 to pull the mirror tilting section14 up from this state. Then, the mirror tilting section 14 pivotsclockwise with a position of abutment between the upper end of theouter-pivot concave surface-forming annular wall 123 of the housingfront 22A and the far end surface 104 a at a right-side position of themirror tilting section 14 in FIG. 7 as a support point, whereby theinner pivot 88 is about to be released from the spherical jointcoupling. With the pivoting of the mirror tilting section 14, theadjustment nut 36 is slightly pulled up. However, in FIG. 30, topsurfaces 147 a of the protrusions 147 immediately abut on and are lockedby a lower surface 149 a of the protrusion abutment portion 149, andthus the pull-up of the adjustment nut 36 is stopped. As a result, thespherical joint coupling between the convex sphere 36 a of theadjustment nut 36 and the concave sphere 66 is cancelled. Also, thespherical joint coupling between the pivot convex 58 and the pivotconcave 60 of the inner pivot 88 is cancelled. Consequently, the mirrortilting section 14 comes off from the tilting support section 12. Atthis time, the claws 145 of the adjustment nut 36 remain threadablyconnected to the male thread member 24 on the tilting support section 12side without coming off from the male thread member 24. When the mirrortilting section 14 is pulled up as described above, the protrusions 147are locked by the protrusion abutment portion 149, whereby a pull-upforce is applied to the protrusions 147. However, the protrusions 147are joined to the barrel 140 and thus the legs 143 are prevented frombeing forcibly pressed. Consequently, deformation and/or breakage of thelegs 143 can be prevented. Also, the length of the protrusions 147 inthe axial direction of each adjustment nut 36 or 38 is longer than thelength of the protrusions 147 in the circumferential direction of theadjustment nut 36 or 38. In other words, the protrusions 147 are flat inthe circumferential direction of the adjustment nut 36 or 38 and areelongated in the axial direction of the adjustment nut 36 or 38.Therefore, even if the protrusions 147 are locked by the protrusionabutment portion 149 and a pull-up force is thereby applied to theprotrusions 147, deformation and/or breakage of the protrusions 147 isprevented because a strength of the protrusion 147 is high relative tothe pull-up force.

As described above, the four protrusions 147 are disposed at equalintervals (equally spaced by 90 degrees) in the circumferentialdirection of the adjustment nut 36 or 38. If the number of protrusions147 is, for example, two (equally spaced by 180 degrees), when acircumferential edge of the mirror tilting section 14 is pulledobliquely upward for replacement of the mirror tilting section 14,depending on the rotational position of the adjustment nut 36 or 38relative to the male thread member 24 or 26, none of the protrusions 147does not abut on the protrusion abutment portion 149 until theadjustment nut 36 or 38 is largely inclined relative to the male threadmember 24 or 26. Thus, deformation or breakage of the legs 143 easilyoccurs. On the other hand, if the protrusions 147 are disposed atequally-spaced four or more positions in the circumferential directionof the adjustment nut 36 or 38, regardless of the rotational positionsof the adjustment nut 36 or 38, any of the four or more protrusions 147abuts on the protrusion abutment portion 149 before the adjustment nut36 or 38 is largely inclined relative to the male thread member 24 or26. Therefore, before the adjustment nut 36, 38 is largely inclined, thespherical joint coupling between the convex sphere 36 a or 38 a of theadjustment nut 36 or 38 and the concave sphere 66 or 68 is cancelled,and thus, the adjustment nut 36 or 38 can be removed from the mirrortilting section 14, preventing deformation and/or breakage of the legs143.

By the way, in case the protrusions 147 have both a function thatprevents rotation relative to the worm wheel 32 and a function thatprevents the adjustment nut 36 from coming off from the male threadmember 24, a travel distance of the adjustment nut 36 is limited by thecoming-off prevention function. As a result, a mirror surface angleadjustment range (swing angle) is narrowed. As a countermeasuretherefor, in this embodiment, as can easily be understood from FIG. 30,with the protrusions 147 abutting on the protrusion abutment portion149, the protrusions 147 are disposed at respective positions above thetop of the male thread member 24. Consequently, compared to the casewhere with the protrusions 147 abutting on the protrusion abutmentportion 149, the protrusions 147 are disposed at positions not above thetop of the male thread member 24, the travel distance until theprotrusions 147 abut on the protrusion abutment portion 149 is long. Asa result, decrease of the mirror surface angle adjustment range issuppressed. Also, the protrusions 147 are disposed at positions of aheight immediately above the legs 143 in the lower portion of the barrel140. Consequently, compared to the case where the protrusions 147 aredisposed at higher positions in the barrel 140, the travel distanceuntil the protrusions 147 abut on the protrusion abutment portion 149 islong. Consequently, also, decrease of the mirror surface angleadjustment range is suppressed. Also, since the protrusion abutmentportion 149 is formed in the housing rear 22B, compared to the casewhere the protrusion abutment portion 149 is formed in the worm wheel 32received in the actuator housing 22, the travel distance until theprotrusions 147 abut the protrusion abutment portion 149 is long.Consequently, also, decrease of the mirror surface angle range issuppressed.

Although the coming-off prevention configuration and the coming-offprevention operation on the adjustment nut 36 side has been describedabove, a coming-off prevention configuration and corning-off preventionoperation on the adjustment nut 38 side are similar to those of theadjustment nut 36 side. Also, when the mirror tilting section 14 istilted in an upper direction to a maximum angle position, the adjustmentnut 38 enters a state that is similar to that in FIG. 30.

Also, in the pivot convex 58, slits 151, which are illustrated in FIG.31, can be formed instead of the grooves 125 illustrated in FIG. 16. Inthis case, the slits 151 make the pivot convex 58 easily elasticallydeform. Therefore, in conjunction with the slits 98 making the pivotconcave annular wall 96 easily elastically deform, the pivot convex 58can be held in the pivot concave 60 with much less backlash, in a statein which the pivot convex 58 is forcibly fitted in the pivot concave 60.In the forcibly-fitted state, the pivot concave annular wall 96 catchesthe pivot convex 58 by means of an elastic force of the pivot concaveannular wall 96. Also, the pivot convex 58 pushes and expands the pivotconcave annular wall 96 by means of an elastic force of the pivot convex58. Therefore, the pivot concave annular wall 96 and the pivot convex 58provide a predetermined pressing force to each other. Since both thepivot convex 58 and the pivot concave annular wall 96 easily elasticallydeform, the support of the mirror tilting section 14 by the outer pivot90 is more uniformized in the circumferential direction of the outerpivot 90. Consequently, the chatter vibration suppression effectprovided by the outer pivot 90 is more enhanced. The slits 151 may beprovided only on the pivot convex 58 side while no slits 98 are providedin the pivot concave annular wall 96. In this case, in the forciblyfitted state, the pivot convex 58 pushes and expands the pivot concaveannular wall 96 by means of the elastic force of the pivot convex 58,and thus provides a predetermined pressing force to the pivot concave60.

Although the above embodiment has been described in terms of the casewhere this invention is applied to a mirror surface angle adjustmentmechanism that employs multiple, inner and outer, pivots, this inventionis applicable also to a mirror surface angle adjustment mechanism thatemploys a single pivot. The above embodiment has been described in termsof the case where this invention is applied to a tilting deviceincluding a mirror tilting section configured by a mirror being held bya mirror holder. However, this invention is applicable also to a tiltingdevice including a mirror tilting section configured by a mirror holderholding a mirror being held by a component called, e.g., a plate pivot,like the tilting devices described in Japanese Patent Laid-Open Nos.2014-159221 and 2014-159222 according to patent applications filed bythe present applicant. Although the above embodiment has been describedin terms of the case where this invention is applied to a motor-driven,remote control-type mirror surface angle adjustment mechanism, thisinvention is applicable also to a manual-type (e.g., a type in which amirror surface is manipulated directly with hands, a wire-manipulationremote control type or a lever-manipulation remote control type) mirrorsurface angle adjustment mechanism. Although the above embodiment hasbeen described in terms of the case where this invention is applied to aview angle adjustment mechanism in which a view element is a mirror,this invention is applicable also to a view angle adjustment mechanismin which a view element is a camera (e.g., a vehicle-mounted camera) oranother view element. Although the above embodiment has been describedin terms of the case where this invention is applied to an outer mirrorfor an automobile, this invention is applicable also to an inner mirrorfor an automobile. Also, this invention is applicable also to a mirrordevice or any of other view devices for use other than an automobile. Inthis invention, which of a convex shape and a concave shape of a pivotis disposed on the view element tilting section side and which of theconvex shape and the concave shape is disposed on the tilting supportsection side can arbitrarily be selected.

What is claimed is:
 1. A view angle adjustment mechanism for a viewdevice, the view angle adjustment mechanism being configured to supporta view element tilting section holding a view element by a tiltingsupport section via a pivot, so as to be capable of adjusting a viewangle of the view element, wherein: the pivot is assembled by forciblefitting between a pivot convex and a pivot concave; the pivot convexincludes a spherical surface; the pivot concave includes: a firstsurface portion, a second surface portion and a third surface portion;wherein the first surface portion is defined by a first conical surfacearea having a full circular conic section that extends around a centeraxis of the pivot concave, the second surface portion is defined by asecond conical surface area having a full circular conic section thatextends around the center axis of the pivot concave, and the thirdsurface portion is defined by an intermediate surface area extendingbetween the first conical surface area and the second conical surfacearea in a direction of the center axis of the pivot concave, wherein thefirst conical surface area and the second conical surface area arearranged so as to face in respective directions opposite to each otheralong the center axis of the pivot concave; and the spherical surface ofthe pivot convex is inscribed in the first conical surface area and thesecond conical surface area of the pivot concave.
 2. The view angleadjustment mechanism according to claim 1, wherein at least one of thepivot convex and the pivot concave is divided in a circumferentialdirection by a slit formed in an axial direction in the at least one ofthe pivot convex and the pivot concave.
 3. The view angle adjustmentmechanism according to claim 2, wherein the slit of the pivot concave isformed at each of three positions equally spaced in the circumferentialdirection.
 4. The view angle adjustment mechanism according to claim 1,wherein a gap formed between the pivot convex and the pivot concave at aposition between two positions at which the pivot convex is inscribed inthe pivot concave forms a grease reservoir.
 5. The view angle adjustmentmechanism according to claim 4, wherein the gap is formed continuouslyaround a periphery of the spherical surface of the pivot convex.
 6. Theview angle adjustment mechanism according to claim 1, wherein each ofthe first conical surface area and the second conical surface area has atrapezoidal shape with respect to a side view that is orthogonal to across-sectional plane taken across the center axis of the pivot concave.7. The view angle adjustment mechanism according to claim 1, wherein oneof the first conical surface area and the second conical surface area isprovided at a closed top-end of the pivot concave and the other of thefirst conical surface area and the second conical surface area isprovided at an opened lower-end of the pivot concave through which thepivot convex is inserted.
 8. The view angle adjustment mechanismaccording to claim 1, wherein the intermediate surface area is acylindrical surface.